Customizable Three-Dimensional Printed Zerovalent Iron: An Efficient and Reusable Fenton-like Reagent for Florfenicol Degradation.

Zerovalent iron (Fe0)-based Fenton-like technology has great potential for treating recalcitrant organic pollutants (ROPs) in wastewater. However, rapidly and precisely manufacturing Fe0-based materials with the desired geometries is challenging. Herein, novel three-dimensional printed Fe0 (3DP-Fe0) and bimetallic 3DP-Ni/Fe0 were customized by 3D printing for efficient Fenton-like degradation of florfenicol (FLO), a typical antibiotic in wastewater. 3DP-Ni/Fe0 with hydrogen peroxide (H2O2) exhibited superior reactivity toward FLO than 3DP-Fe0, generating hydroxyl radicals (·OH) and atomic hydrogen to achieve >90% dehalogenation and >70% total organic carbon removal within 10 min. The resulting degradation intermediates possessed lower antibacterial activity than FLO and did not cause resistance gene proliferation in activated sludge. The Fenton-like activity of 3DP-Ni/Fe0 was similar across different shapes but increased with increasing porosity and size. Compared with powdered Ni/Fe0, 3DP-Ni/Fe0 exhibited faster electron transfer during Fe(II)/Fe(III) cycling, which increased the utilization efficiency of dissolved Fe2+ and H2O2 for ·OH production. Moreover, 3DP-Ni/Fe0 could be reused >150 times, 5-fold more than powdered Ni/Fe0, owing to its lower metal ion release and Fe0 depletion. 3DP-Ni/Fe0 with H2O2 can also efficiently remove chemical oxygen demand from real wastewater and other ROPs (e.g., acetaminophen, carbamazepine, thiamphenicol, and tetrabromobisphenol A).

Special Distribution of Nanoplastics in the Central Nervous System of Zebrafish during Early Development.

There is growing concern about the distribution of nanoplastics (NPs) in the central nervous system (CNS), whereas intrusion is poorly understood. In this study, fluorescent-labeled polystyrene NPs (PS-NPs) were microinjected into different areas of zebrafish embryo to mimic different routes of exposure. PS-NPs were observed in the brain, eyes, and spinal cord through gametal exposure. It indicated that maternally derived PS-NPs were specially distributed in the CNS of zebrafish during early development. Importantly, these NPs were stranded in the CNS but not transferred to other organs during development. Furthermore, using neuron GFP-labeled transgenic zebrafish, colocalization between NPs and the neuron cells revealed that NPs were mostly enriched in the CNS surrounded but not the neurons. Even so, the intrusion of NPs into the CNS induced the significant upregulation of some neurotransmitter receptors, leading to an inhibited effect on the movement of zebrafish larvae. This work provides insights into understanding the intrusion and distribution of NPs in the CNS and the subsequent potential adverse effects.

Maternal methylosome protein 50 is essential for embryonic development in medaka Oryzias latipes.

Methylosome protein 50 (Mep50) is a protein that is rich in WD40 domains, which mediate and regulate a variety of physiological processes in organisms. Previous studies indicated the necessity of Mep50 in embryogenesis in mice Mus musculus and fish. This study aimed to further understand the roles of maternal Mep50 in early embryogenesis using medaka Oryzias latipes as a model. Without maternal Mep50, medaka zygotes developed to the pre-early gastrula stage but died later. The transcriptome of the embryos at the pre-early gastrula stage was analyzed by RNA sequencing. The results indicated that 1572 genes were significantly upregulated and 741 genes were significantly downregulated in the embryos without maternal Mep50. In the differentially expressed genes (DEGs), the DNA-binding proteins, such as histones and members of the small chromosome maintenance complex, were enriched. The major interfered regulatory networks in the embryos losing maternal Mep50 included DNA replication and cell cycle regulation, AP-1 transcription factors such as Jun and Fos, the Wnt pathway, RNA processing, and the extracellular matrix. Quantitative RT-PCR verified 16 DEGs, including prmt5, H2A, cpsf, jun, mcm4, myc, p21, ccne2, cdk6, and col1, among others. It was speculated that the absence of maternal Mep50 could potentially lead to errors in DNA replication and cell cycle arrest, ultimately resulting in cell apoptosis. This eventually resulted in the failure of gastrulation and embryonic death. The results indicate the importance of maternal Mep50 in early embryonic development, particularly in medaka fish.

Alternative splicing of medaka bcl6aa and its repression by Prdm1a and Prdm1b.

Bcl6 and Prdm1 (Blimp1) are a pair of transcriptional factors that repressing each other in mammals. Prdm1 represses the expression of bcl6 by binding a cis-element of the bcl6 gene in mammals. The homologs of Bcl6 and Prdm1 have been identified in teleost fish. However, whether these two factors regulate each other in the same way in fish like that in mammals is not clear. In this study, the regulation of bcl6aa by Prdm1 was investigated in medaka. The mRNA of bcl6aa has three variants (bcl6aaX1-X3) at the 5'-end by alternative splicing detected by RT-PCR. The three variants can be detected in adult tissues and developing embryos of medaka. Prdm1a and prdm1b are expressed in the tissues and embryos where and when bcl6aa is expressed. The expression of prdm1a was high while the expression of bcl6aa was low, and vice versa, detected in the spleen after stimulation with LPS or polyI:C. In vitro reporter assay indicated that bcl6aa could be directly repressed by both Prdm1a and Prdm1b in a dosage-dependent manner. After mutation of the key base, G, of all predicted binding sites in the core promoter region of bcl6aa, the repression by Prdm1a and/or Prdm1b disappeared. The binding site of Prdm1 in the bcl6aa gene is GAAAA(T/G). These results indicate that both Prdm1a and Prdm1b directly repress the expression of bcl6aa by binding their binding sites where the 5'-G is critical in medaka fish.

Toward Accurate Extraction of Respiratory Frequency From the Photoplethysmogram: Effect of Measurement Site.

Background: It is known that the respiration-modulated photoplethysmographic (PPG) signals could be used to derive respiratory frequency (RF) and that PPG signals could be measured from different body sites. However, the accuracy of RF derived from PPG signals of different body sites has not been comprehensively investigated. Objective: This study aims to investigate the difference in the accuracy of PPG-derived RFs between measurements from different body sites, respectively, for normal and deep breathing conditions. Methods: Under normal and deep breathing patterns, the PPG signals were recorded sequentially in a randomized order from six body sites [finger, wrist under (anatomically volar), wrist upper (dorsal), earlobe, and forehead] of 36 healthy subjects. Simultaneously, the reference respiratory signal was measured by a respiratory belt on the chest. Using the frequency demodulation approach, respiratory signals were extracted from PPG signals for calculating RF by power spectral density. The bias between PPG-derived and reference RFs was then analyzed statistically using analysis of variance and non-parametric tests, Bland-Altman analysis, and linear regression to investigate the difference in RF bias between different sites. Results: The RF bias was significantly influenced by the breathing pattern and measurement site (both p < 0.001). Under normal breathing, the RF bias was insignificant in the arm, forehead, and wrist under (all p > 0.05) and significant in the other sites (all p < 0.05). Significant linear relationship between PPG-derived and reference RFs existed at all the sites (p < 0.001) except the wrist upper (p > 0.05). The linearity between PPG-derived and reference RFs was highest at the forehead (slope of best-fit line: 0.90, R 2: 0.64), followed by the earlobe, finger, arm, and wrist under (slope: 0.71, R 2: 0.40). Under deep breathing, there was no significant RF bias in all the measurement sites (p > 0.05) except forehead (p = 0.048). The effect of measurement site on RF bias was not significant (p > 0.05). The finger had the smallest RF bias and the narrowest limits of agreement. Conclusion: This study has demonstrated that the accuracy of PPG-derived RF depends on the measurement site and breathing pattern. The best sites are the forehead and finger, respectively, for normal and deep breathing patterns.

Production of a value added compound from the H-acid waste water-Bioflocculants by Klebsiella pneumoniae.

A novel strain (designated as ZCY-7) which could convert H-acid into bioflocculants was isolated from H-acid wastewater sludge. Conditions for bioflocculants production were optimized by response surface methodology (RSM) and determined to be inoculum size 9.65%, initial pH 7.0, and CODCr of the H-acid wastewater 520mg/L. The highest flocculating efficiency achieved for kaolin suspension was 95.1%, after 60h cultivation. The yielded bioflocculant was mainly composed of polysaccharide (82.4%) and protein (14.2%), and maintained its flocculating activity in 0.4% (w/w) kaolin suspensions over pH 2-8 and 20-80°C. Fourier transform infrared (FTIR) spectra showed that amino, amide and hydroxyl groups were present in the bioflocculant molecules. A viable alternative treatment technology of H-acid wastewater using this novel strain is suggested, which could largely reduce bioflocculants costs. In addition, flocculating mechanism investigation reveals that the bioflocculant could cause kaolin suspension instability by means of charge neutralization firstly and then promoted the aggregation of suspension particles by adsorption and bridge. It is evident from the results that H-acid wastewater could be used as a source to manufacture bioflocculants.

Production of a bioflocculant from chromotropic acid waste water and its application in steroid estrogen removal.

A novel strain (designated as SW-2) which could convert chromotropic acid into bioflocculants was isolated from chromotropic acid wastewater. Conditions for bioflocculants production were optimized by response surface methodology (RSM) and determined to be inoculum size 7.74%, initial pH 6.9, and CODCr of the chromotropic acid wastewater 425mg/L. The yielded bioflocculant was primarily consisting of polysaccharide and protein. It could maintain its flocculating activity to 0.4% (w/w) kaolin suspensions over pH 3-9 and 20-80°C. In addition, conditions for the removal of estrogens with the bioflocculant were investigated and determined to be bioflocculant dosage 50mg/L, initial pH 3, reaction time 60min, and temperature 45°C. Under these optimal conditions, the removal efficiencies of E1, E2, EE2, and E3 were 87%, 92%, 88% and 96%, respectively. The bioflocculant was shown to offer a promising alternative method of removing estrogens from water in pretreatment applications.